The automatic turret type winder is used for winding of continuously arriving tapes, threads, or bands onto a bobbin. In general, on the turret type winder, a pair of bobbin holders—also known as spindles—are mounted on the opposite ends of a rotatable turret mounted on suitable machine frame. Each spindle is alternately displaced from the normal winding position to the doffing position by every half rotation of the turret. The turret keeps on rotating in the same direction at required time intervals. Each spindle needs precisely controlled rotation around its own axis, so may be driven independently by an electric motor through a suitable mechanism such as a belt and pulley arrangement or with an independent direct driving electrical motor system. Conventionally, the encoders or other suitable devices are mounted on the motor for monitoring the motor revolutions, and the signal is communicated to an electronic controller with the help of a suitable cable. The controller further sends the electrical signals to the inverter/drive of the active motor which determines the power to be given for the motor driving the spindle.
The conventional winders of the above type are disclosed in the U.S. Pat. Nos. 5,228,630, 4,765,552 and European Patent 861800A2. Other relevant inventions are disclosed in U.S. Pat. Nos. 5,228,630, 5,407,143, WO98/42607, WO99/18024, and DE10303641. These inventions, by and large, disclose methods and winders to transfer yarn on an empty bobbin in a continuous yarn winding operation. However, they do not teach how to position the empty bobbin with precision.
Automatic turret type winders were introduced for providing bobbins of polyolefin flat/fibrillated yams and to improve efficiency, reduce wastages. Automatic changeover process replaces spindle carrying yarn bobbin with the spindle carrying an empty bobbin.
In these conventional automatic winders, the turret is rotated by using a clutch and a pulley in synchronicity. Turret rotation is performed by releasing clutch and transferring the driving force to the pulley for rotation. After the turret rotation, correct positioning of empty bobbin is done by drifting bobbin in reverse direction towards the CAM box pressure roller. Ideally, spindle is positioned such that pressure roller should exert pressure uniformly on spindle present for winding. Reverse movement of turret carrying spindle is controlled according to the pre-set time and speed parameters in the control system. Practically, in conventional systems, turret movement is not uniform, and therefore not as smooth as required, due to change in mechanical condition. Machines of the type being discussed here are generally not operated under entirely dust-free environment. Therefore, as time progresses, accumulation of foreign particles on the mechanical components of the machinery increases even after taking abundant precaution to clean and maintain the machine. Accumulation of particulate matter provides hindrance to smooth motion of moving elements over a period of time. In other words, the system's resistance to smooth movement of components increases due to general wear and tear and accumulation of particulate matter.
For instance, a turret could become jammed due to accumulation of dust particles or may become tightened or loosened than required during maintenance cycle, leading to a turret rotation that is either faster or slower than desired or jerky. These mechanical glitches often result in improper spindle positioning relative to the pressure roller. Improper positioning causes a gap between the spindle bobbin which is ready to be wound and the pressure roller, which in turn produces uneven winding tension and therefore non-uniform package density.
Second, the stated problem in conventional winding system develops when the turret motion pushes the pressure roller extra in reverse direction. Similar to prior stated problem, this condition also produces variation in winding tension and formation of groves or undulations on the bobbin surface.
Therefore, there is a need to provide a method to position spindle precisely in turret type automatic winder automatic method, especially a method to identify correct stationing position of turret spindle after reverse movement post doffing.
There is also a need to provide a system that reduces possibility of turret positioning itself at an intermediate location, thereby leaving a gap between the spindle and the pressure roller, or positioning itself past its desired location, thereby exerting extra pressure on the roller.